The present invention relates to apparatus for feeding insulation (or duct) board to a grooving machine to create preformed duct sections. More particularly, the present invention constitutes an improvement over the machine described and claimed in commonly assigned U.S. Pat. No. 3,875,835 issued to Edwin E. Roberts.
The Roberts machine comprised feeding apparatus including an elevator assembly, a pair of aligning assemblies, and a transfer assembly, along with grooving apparatus. As a practical matter, it became necessary to subdivide the insulation board feeding mechanisms from the actual grooving or cutting mechanisms as shown in the Roberts machine. The resulting grooving machine was essentially the same as section 22 of the patented machine, having a powered infeed section, grooving knives with a backing roller, and a drawing assembly comprised of powered rollers to draw the board section through the cutting assembly. It is the board feeding apparatus to which the present invention is directed.
The transfer assembly of the Roberts machine comprised a horizontal bar extending substantially the width of the machine. This feed bar was reciprocated through a short stroke by an eccentric. The length of the stroke was only sufficient to move the board into contact with the powered rolls of the grooving assembly. The elevator assembly, transfer assembly and alignment mechanism were all driven through chains and sprockets by three separate motors.
Variations in thickness and density which invariably occur in the formation of such insulation boards, produced significant problems for the Roberts machine. A thickness variation at a particular board location of as small as 1/32", cumulative through a full stack of boards, could produce a positional variation across the 8' width of the feeder exceeding the 1" thickness of the board. The elongated feed bar would, accordingly, engage and attempt to feed the top two boards resulting in jamming. In addition, density variations (from variances in fiber and/or binder distribution) created problems for the grooving knives. Due to the short stroke of the feed bar, the only motive force being applied to the board at the time the blades initially contacted the board was by infeed rollers 74 and 76. These density variations resulted in greater resistance being experienced by one or more knives than by the other knives causing the board to skew. Such skewing again caused jamming of the equipment and resulted in creation of a scrap part.
The last problem associated with the Roberts machine was the cost. The three separate motors, plus the chain and sprocket drives, made the apparatus very expensive to manufacture. This high entry cost associated with getting into the duct-fabrication-from-insulation-board business significantly limited the growth of the insulation board market.